1. Field of the Invention
Aspects of the present invention relate to wireless communication technology, and more particularly to a method for achieving route optimization when a dual IPv4 mobile node (MN) is connected with an IPv6-only network, wherein the route optimization allows packets to traverse a route shorter than a default route through a home agent (HA) using bidirectional tunneling, thus leading to better bandwidth utilization.
2. Description of the Related Art
An IP address is used to identify both a node and its location inside an IP network. Whenever a mobile node (MN) moves inside the network, its IP address must change as well. Many approaches have been proposed to support mobility in IP networks, sometimes designed to solve only specific problems. Handover latency, signaling, and packet loss are the major issues that need to be addressed. Using the existing technology, route optimization is not available and the communication between a MN and a correspondent node (CN) is possible only using bidirectional tunneling via a home agent (HA). The following subsections describe an existing communication path between a MN and a CN, when the MN is connected with an IPv6-only network. The various operations undergone in the existing technology can be stated as follows:                i) When an IPv4-capable dual mobile node (MN) enters an IPv6-only network, the dual MN obtains an IPv6 address.        ii) On receiving a router advertisement (RA), the dual MN realizes that the network is an IPv6-only network. The MN sends a Binding Update (BU) containing the IPv6 address of the IPv4-capable dual MN to its HA.        iii) On receiving the IPv6 address of the MN, a bidirectional tunnel is established between the HA and the dual MN in the IPv6-only network.        iv) All packets to and from the node go via the established bidirectional tunnel.        
Since all of the packets that pass to and from a MN traverse a bidirectional tunnel between an HA and a MN, the HA is overloaded. If the HA does not support an IPv4-over-IPv6 tunneling, a mobile host cannot communicate with any CN.